class Test_calculate_difference(IrisTest):
"""Test the calculate_difference method."""
def setUp(self):
"""Set up cube."""
data = np.array([[1, 2, 3],
[2, 4, 6],
[5, 10, 15]])
self.cube = set_up_cube(data, "wind_speed", "m s-1")
self.plugin = DifferenceBetweenAdjacentGridSquares()
def test_x_dimension(self):
"""Test differences calculated along the x dimension."""
expected = np.array([[1, 1],
[2, 2],
[5, 5]])
result = self.plugin.calculate_difference(self.cube, "x")
self.assertIsInstance(result, Cube)
self.assertArrayAlmostEqual(result.data, expected)
def test_y_dimension(self):
"""Test differences calculated along the y dimension."""
expected = np.array([[1, 2, 3],
[3, 6, 9]])
result = self.plugin.calculate_difference(self.cube, "y")
self.assertIsInstance(result, Cube)
self.assertArrayAlmostEqual(result.data, expected)
def test_missing_data(self):
"""Test that the result is as expected when data is missing."""
data = np.array([[1, 2, 3],
[np.nan, 4, 6],
[5, 10, 15]])
cube = set_up_cube(data, "wind_speed", "m s-1")
expected = np.array([[np.nan, 2, 3],
[np.nan, 6, 9]])
result = self.plugin.calculate_difference(cube, "y")
self.assertIsInstance(result, Cube)
self.assertArrayAlmostEqual(result.data, expected)
def test_masked_data(self):
"""Test that the result is as expected when data is masked."""
data = ma.array([[1, 2, 3],
[2, 4, 6],
[5, 10, 15]],
mask=[[0, 0, 0],
[1, 0, 0],
[0, 0, 0]])
cube = set_up_cube(data, "wind_speed", "m s-1")
expected = ma.array([[1, 2, 3],
[3, 6, 9]],
mask=[[1, 0, 0],
[1, 0, 0]])
result = self.plugin.calculate_difference(cube, "y")
self.assertIsInstance(result, Cube)
self.assertArrayEqual(result.data, expected)
self.assertArrayEqual(result.data.mask, expected.mask)
class Test_gradient_from_diff(IrisTest):
"""Test for correct behaviour when calculating a gradient"""
def setUp(self):
"""Set up cube."""
data = np.array([[1, 2, 3],
[2, 4, 2],
[5, 10, 15]])
x_coord = DimCoord(2.*np.arange(3), "projection_x_coordinate")
y_coord = DimCoord(2.*np.arange(3), "projection_y_coordinate")
self.cube = iris.cube.Cube(data, "wind_speed", units="m s-1",
dim_coords_and_dims=[(y_coord, 0),
(x_coord, 1)])
self.plugin = DifferenceBetweenAdjacentGridSquares(gradient=True)
def test_basic(self):
"""Test contents and metadata"""
expected = np.array([[0.5, 0.5, 0.5],
[2.0, 0.0, -2.0],
[2.5, 2.5, 2.5]])
xdiff = self.plugin.calculate_difference(self.cube, "x")
result = self.plugin.gradient_from_diff(xdiff, self.cube, "x")
self.assertArrayAlmostEqual(result.data, expected)
self.assertEqual(result.name(), "gradient_of_wind_speed")